x86: fix implicit include of <linux/topology.h> in vsyscall_64

In removing the presence of <linux/module.h> from some of the
more common <linux/something.h> files, this implict include
of <linux/topology.h> was uncovered.

  CC      arch/x86/kernel/vsyscall_64.o
  arch/x86/kernel/vsyscall_64.c: In function ‘vsyscall_set_cpu’:
  arch/x86/kernel/vsyscall_64.c:259: error: implicit declaration of function ‘cpu_to_node’

Explicitly call it out so the cleanup can take place.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>